Generally when electronic components are mounted on a printed board, firstly a cream solder is printed on a certain electronic pattern disposed on the printed board. This printing of cream solder is carried out by screen printing by use of a silkscreen in which are formed multiple holes that correspond to the electrode pattern. The electronic components are provisionally held on the cream solder-printed board by viscosity of the cream solder. Thereafter, the printed board is carried to a reflow furnace, and soldering is performed as the printed board passes through a certain reflow process. In recent years, inspection of the condition of the solder printing has been performed during a stage prior to conveyance to the reflow furnace.
During this processing, there are concerns that manufacturing errors, shrinkage-stretching over time, and the like may occur for the silkscreen; and difficulties arise where perfect matching does not occur between the positions of the electrode pattern on the printed board and the positions of the holes formed in the silkscreen. For this reason, there is concern that the solder may be printed at positions displaced from the electrode pattern. Thus technology has been proposed (e.g., see Patent Citation 1) that finds a shift amount of the silkscreen that results in a minimum of the total of parallel movement displacement amounts of all solders printed on the board relative to the solder printing positions according to design (ideal printing positions), and performs correction of the printing positions based on this shift amount.
[Patent Citation 1] Unexamined Laid-open Patent Application 2006-5238.
However, when the above-mentioned technology is used, the shift amount is then determined uniformly without regard to the magnitude of the size of the solder. Thus when comparatively small solder is printed on a comparatively small electrode pattern, there is concern that this may result in printing at positions of relatively great displacement from the electrode pattern. As a result, problems occur such as non-printing of solder on the electrode pattern, printing that causes solder to connect together electrode patterns (bridging), and the like; and there are concerns that such problems would result in lowering of manufacturing quality and lowering of yield. Moreover, particularly for miniaturized electrode patterns, there have been further concerns that the frequency of occurrence of bridging and the like may then greatly increase and that manufacturing quality and yield may further decrease.